Rim driven rotary cutter and tree felling head incorporating the same

ABSTRACT

A rim driven circular saw and a drive pinion rotatable about respective ones of a pair of spaced apart parallel axes wherein each of the saw and pinion having projections of gear tooth form about the outer periphery thereof with the teeth of one meshing with those of the other. The teeth on the saw each have a cutting edge set back from the normal intersection of the face and the top land of the teeth. The saw is journalled for rotation on a plate carried by a rigid frame and the plate has a thickness at least no greater than the kerf generated by the saw. The pinion is fabricated from a non-metallic substance such as nylon. Also disclosed is an accumulator type tree felling head incorporating, as the cutting device, a saw of the foregoing type.

This application is related to applicant's U.S. pending application No.605,219, filed Apr. 30, 1984.

FIELD OF INVENTION

This invention relates to an apparatus for cross-cutting treesincorporating an improved rim driven circular saw and new and usefulimprovements in rim driven circular saws.

The present application is closely related to U.S. application Ser. No.605,219 filed Apr. 30, 1984 referred to above and entitled TREE FELLINGHEAD HAVING A RIM DRIVEN ROTARY CUTTER. It is directed to improvementsthereto and more particularly to the configuration and materials for thedriving and driven members of the saw, to apparatus to keep them clean,to the bearing and support arrangements of the saw, and to thecombination of the saw assembly with grapples to form a felling head.

BACKGROUND OF INVENTION

The valuable part of a tree is the butt area where the felling cut ismade and there has been increasing concern over the damage being done tothis area by shear severing devices with the consequence of numerousproposals having been made adapting chain saws and circular centerspindle mounted saw blades and cutting discs on felling heads forcutting trees. Chain saws, however, are fragile and thus subject tofrequent failure. Circular saws, while they are more robust, are alsomore bulky. Also, they usually are run at higher speeds with anattendant increase in safety and saw damage hazards. Because of thesedrawbacks, applicant has adapted the rim driven saw principle. Thesesaws are inherently compact as they do not need a central arbour fordriving purposes. They can be robust in construction and operated atmoderate to low speeds and thus avoid many of the disadvantages as wellas safety and damage hazards associated with high speed, previously usedcircular saws.

One form of rim driven saw for applicant's intended purpose is disclosedin the aforementioned appplication Ser. No. 605,219.

Other rim driven type saws are also known, as for exapmle thosedisclosed in the following patents:

Canadian Patent No. 983,825 issued, Feb. 17, 1976--Jonsson

Canadian Patent No. 994,647, issued Aug. 10, 1976--Wiklund

U.S. Pat. No. 2,490,255, issued Dec. 6, 1949--Chase

U.S. Pat. No. 2,599,495, issued June 3, 1952--Smith

U.S. Pat. No. 2,701,590, issued Feb. 8, 1955--Barker

U.S. Pat. No. 2,804,105, issued Aug. 27, 1957--Stone

U.S. Pat. No. 2,972,363, issued Feb. 21, 1961--Santilli

U.S. Pat. No. 3,930,310, issued, Jan. 6, 1976--Santilli

U.S. Pat. No. 460,679, issued Oct. 6, 1891--Hammond

In addition to the foregoing there is commercially available a treefeller incorporating a rim driven saw distributed in Canada by RisleyEquipment Ltd. of Grande Prairie, Alberta and is sold under the tradename "RotoSaw".

Applicant's device, as will be found hereinafter, incorporates a numberof features and combinations thereof which distinguishes over theforegoing known devices.

SUMMARY OF INVENTION

The general purpose of the present invention is to provide an improvedtree cutting rim driven circular saw and a tree felling headincorporating the same.

In accordance with one aspect of the present invention the saw blade andthe drive pinion therefore are located substantially in the same plane.The drive pinion incorporates conventionally formed gear teeth and thesaw teeth combine conventional gear tooth and saw tooth technology. Inthe saw tooth the trailing face and flank is of conventional gear formto mate with the driving pinion and the leading face, flank and the topland are shaped to provide suitable hook, sharpness, and clearanceangles according to conventional saw tooth technology. One of thedrawbacks of this design is that under certain conditions, for examplewhen the power source driving the pinion is decelerated rapidly orsuddenly stopped, the inertia of the saw results in the saw trying todrive the pinion in which case contact may be made between it and thecutting edge of the saw teeth. This can cause wear or damage on thecutting edge and/or the drive pinion teeth. This, however, can bealleviated by using an overrunning clutch in the drive pinion mounting.

In another aspect of the present invention there is a novel tooth formthat avoids possible contact as described in the foregoing between thecutting edge of the saw teeth and the teeth on the drive pinion thuseliminating that source of wear and the need for an overrunning clutchas mentioned above.

The novel tooth form is such that the teeth or cutting projections,located about the perimeter of a circular saw blade, can be engaged fordriving rotation by a drive pinion which itself has conventional gearteeth thereabout. This novel design further ensures positive meshingengagement of the pinion with the circular saw at all times includingabrupt stoppage of the drive pinion or reverse rotation of the saw bladefrom its normal direction of rotation whilst at all times avoidingcontact between the cutting edge of the saw blade projections and theteeth of the drive pinion.

In accordance with this aspect of the invention, the saw blade is of atype including a circular body portion, which may be either an annulusor disc, and a plurality of equally spaced apart and alike cuttingprojections which extend radially outwardly from a periphery of the bodyportion. Each of the projections has a profile of a conventional geartooth that includes, relative to the direction of saw rotation, a topland portion, a leading and trailing face portion and a leading andtrailing flank portion. The leading face portion is, however, modifiedby a cut out which extends from proximate a juncture of the leading faceand flank portions to a line on the top land. This line locates thecutting edge of the saw and the aforementioned cut out can be such thatthe said edge is set back from the normal point of intersection of thetop land and the leading face of the gear tooth thus avoidinginterference with the pinion.

It is desirable to have the leading flank of the projections leftunmodified to the extent that the contact ratio between the gear teethof the pinion used to drive the saw blade and the projections on the sawblade is one or more when the rotation is opposite to the cuttingdirection. The modified portion can also be shaped to provide a suitablehook angle for the leading edge of the cutter.

Advantageously, the top land of the modified cutting projections asabove described can itself be modified so as to provide a clearanceangle rearward of the cutting edge in order to avoid excess frictionbetween the cutting projections and the wood in process. The location ofthe edge can be adjusted if necessary to optimize the arrangement.

While there are many gear profiles which will provide satisfactoryconjugate action the involute type is preferred and is displayed. Itsdominance in industry will enhance the utility of this invention.

The teeth of the drive pinion display an involute profile and meshinglyengage with the cutting projections of the blade, as modified. Asindicated above, the set back of the cutting edge from the otherwisenormal intersection of a gear tooth top land with its leading face is adistance sufficient to avoid contact of the cutting edge with the teethof the driving pinion.

The cutting edges can be an integral part of the cutting projectionswith brazed on carbide or other hard substance or they can be detachablybolted on tips each incorporating one or more cutting edges with orwithout carbide edges or the like. The multi edge cutting tips that aredetachably mounted can be reversible to prolong the life of the cutter.

In the applicant's device, the mating of the pinion and the saw teeth isin the open and without conventional lubrication. The components aresubject to contamination, such as wood chips from the saw, withresulting shocks to the system and accelerated wear rates. To reducethese problems to economically acceptable proportions applicant'spreference is for the pinion to be made of non-metallic material such asnylon. This material is light, inexpensive, and its strength and wearcharacteristics can be enhanced if needed by the addition of materialssuch as glass fibre and PTFE (Polytetrafluoroethylene). It also acts asa sacrifical member to limit loading on other components of the system.Other synthetics or rubber compounds may also prove effective in thisapplication. Steel, cast iron, or bronze may also have application.

The removal of chips or other debris from between the cutting teethand/or saw support frame are also provided for. Two types of cleaningdevices are proposed, while, of course, there may be others. One is anidler sprocket having projections thereon that mate with the teeth ofthe cutter and clears them of mterial that is caught between the teeth.In addition, or alternative thereto, an air jet may be used to blow awaythe debris resulting from cutting and/or the support frame for thecutter may be designed to permit easy escape of the chips duringcutting.

According to a still further aspect of the present invention, thecutting disc, i.e. the circular saw blade, is supported on a base memberand driven at or near the outer periphery.

The saw blade is fully supported and journalled on a base plate which isfixed to a supporting arm used to mount the cutting assembly on theframe of the felling head. The rotatable saw blade is supported on thebase plate by bearing means which include an outer bronze bearing ring.This ring carries any upward loads from the saw blade and can shareloads in the plane of the saw with a central bronze bearing. A thirdbronze bearing at the outer edge of the saw carries any downward loadson the saw. A lubrication line, through the base plate, carries oil tothe central bearing from which it flows back to the bearings at theperiphery. Applicant has found during field testing of a prototype ofthe subject saw that very little wear takes place on the aforementionedouter bronze rings and further that the central bronze ring carries mostloads. It has been further discovered that efficient rotational speedsof the saw blade cause the loads on the central bronze bearing to exceednormal pressure-velocity ratings for such materials. It is therefore animprovement to replace the central bronze bearing with a ball or rollerbearing.

While the saw can be operated over a wide range of speeds, a low tomoderate speed arrangement is preferred as it reduces damage to teethand the danger potential of high speed saws.

The required power is applied through a conventional hydraulic motorunit of sufficient power to effect cutting and to overcome extraneousforces such as those which might be exerted by leaning trees.

In the embodiment illustrated in this application, the saw is mounted onan arm which is pivotally connected to a frame which in turn supportspivotal grapple arms. The saw and the arms acting together comprise afelling head. The felling head is carried from tree to tree by a vehicleequiped with mounting forks or a boom as is well known in the art. Itwill be obvious to anyone skilled in the art that the mountingarrangement for this novel saw and the manner of operation andco-operation with the grapples is flexible and can, for instance, besimilar to that illustrated in Canadian patent Nos. 1,135,599 and1,161,342 or the RotoSaw felling head.

LIST OF DRAWINGS

The invention is illustrated by way of example with reference to theaccompanying drawings wherein:

FIG. 1 is an oblique view of a tree felling head incorporating a rimdriven saw in accordance with the present invention;

FIG. 2 is a partial top plan view of the tree cutting mechanism of thetree felling head shown in FIG. 1;

FIG. 3 is similar to FIG. 2 on a somewhat larger scale and showing inmore detail the construction of the cutting mechanism and the locationof the cleaning mechanisms;

FIG. 4 is a partial elevational view of the frame and saw cuttingmechanism illustrated in FIG. 3;

FIG. 5 is a partial sectional view taken essentially along Section V--Vof FIG. 3;

FIG. 6 is a sectional view taken essentially along line VI--VI of FIG.3;

FIG. 7 is a sectional view taken along line VII--VII of FIG. 3;

FIG. 8 is a sectional view taken along line VIII--VIII of FIG. 3;

FIG. 9 is a sectional view taken along line IX--IX of FIG. 3;

FIG. 10 is a partial top plan view illustrating the meshing of the drivepinion with the cutting member having one form of cutting teeth;

FIG. 11 is a partial top plan view of the engagement of the teeth of thedrive sprocket with modified cutting projections on the circular saw;and

FIG. 12 is a partial plan view of a circular saw blade having reversibleand removable cutting tips.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the drawings there is illustrated in FIG. 1, an accumulatortype tree felling head for mounting on the free outer end of a boom orlift forks carried by a mobile vehicle. The felling head includes arigid frame A on which there is mounted a pair of grapple arms B, one ofthe grapple arms having fingers C pivotally mounted thereon foraccumulating trees in a tree accumulating area designated D below whichthere is a horizontal plate E for supporting the butt end of the cuttrees. On the lower end of the frame there is pivotally mounted a treesevering device F.

The severing device (FIG. 2) includes an arm or saw support frame 10pivotally attached to the base of the felling head frame A by a pivotpin 11 and is controllably moved by an hydraulic cylinder unit 12connected thereto. A rotary cutting circular saw 13 (i.e. a circulardisc) is mounted on the support frame 10 in a manner describedhereinafter and is rim driven by an hydraulic motor 14 through pinion 15(see FIG. 8). The teeth 16 of the pinion mate with the combined gear andcutting teeth 17 on the outer periphery of the circular saw. The arm 10has a base plate 20 rigidly secured thereto along with arm component 3and which underlies and supports the circular saw 13.

The circular saw is supported on the base plate 20 by a first annularbearing 23, a second annular bearing 24, and a third annular bearing 25,all of which are concentrically disposed and radially spaced outwardlyfrom one another and the axis of rotation Y--Y of the circular saw.Bearing 23 is mounted on the base plate 20 and engages an annular flange26 projecting downwardly from the circular saw 13. Bearing 24 is securedto the base plate 20 and engages the underlying surface of the saw 13and bearing 25 is secured to the saw blade 13 by way of a plurality ofstuds 27. The annular bearing 25 engages the undersurface of a lip 28 onthe base plate thereby positively retaining the saw blade on the baseplate 20. The bearings 23, 24, 25 are lubricated by a suitable lubricantprovided under pressure by way of passage 29 provided in the base plate.

The circular saw 13 is driven by way of the hydraulic motor 14 (FIG. 7)having the pinion 15 secured thereto and provided with gear teeth 16that are in direct engagement with the rear face 33 of the saw bladecutting teeth 17 (see FIG. 10). The rear face 33 of the cuttingprojection and the gear teeth 17 are appropriately designed for meshingas regular gear teeth. The leading face of the cutting members 17 areprovided with carbide tip cutting edges 34 permanently or detachablysecured thereto.

The saw blade 13 is driven in the direction indicated by arrow B in FIG.3 and chips, which form as a result of cutting, are ejected from theU-shaped channel frame by centrifugal force or by one or both of the twodifferent provisions. One provision consists of an idler 35 (FIG. 6)having projections 36 thereon that mesh with the saw blade teeth 17 soas to drive the chips from between the cutting formation downwardlythrough an opening 37 in the bottom portion of the frame. The secondmeans of ejecting debris from the teeth consists of an air jet directeddownwardly between the cutting formations as illustrated in FIG. 7. Theair jet is directed by way of a conduit 38 downwardly toward the cuttingformations 17 and angularly outward. Such chips are driven through adischarge opening 40 in the frame that extends approximately from pointsD to E as indicated in FIG. 3. The further discharge of chips, resultingfrom cutting, will be removed by centrifugal action through rotation ofthe cutting member, such chips being discharged directly off the sawbeyond approximate section IX--IX and through the partial arcuateopening 40 extending from point D to E on the frame.

From the foregoing and as illustrated in the drawings there is provideda rotary cutting member consisting of a solid disc positively mounted bybearing means on a base plate, lubrication being provided for thebearings and different means provided for discharging the chips during acutting operation.

FIG. 9 is a section taken essentially along line IX--IX of FIG. 3, fromwhich it can be seen the cutting projections 17 extend radially beyondthe base plate 20 with the kerf of the cutting member being slightlygreater than the thickness of the base plate 20 and the saw blade 13.

The saw blade 13, as shown in FIG. 10, has cutting tips 34 which, aspreviously mentioned, can engage the rear face of pinion teeth 16 whenthe pinion is decelerated or stopped rapidly because of the inertialeffects of the saw blade. This could be overcome by having an undercutin the teeth 16 of the pinion but, obviously, such undercut wouldsubstantially weaken the teeth. Another alternative consists of havingthe cutting edge 34 offset rearwardly relative to the direction ofrotation of the saw blade and modify the shape of the cutting formations33 whereby upon deceleration of the pinion the teeth on the saw blademate with the teeth on the pinion preventing direct contact of thecutting edge 34 of the rear face of the pinion teeth. This embodiment isillustrated in more detail in FIGS. 11 and 12.

Referring now to FIGS. 11 and 12 there is illustrated a portion of acircular saw blade 13A having cutting projections or saw teeth 50equally spaced about the outer periphery of the circular saw blade andmeshing with the teeth 16 of the pinion 15. Each saw tooth 50, asillustrated, has an involute gear tooth profile and which, relative topitch circle 51 have leading and trailing flanks 52 and 53,respectively, and a leading face illustrated by broken line 54, a topland portion also illustrated in broken line at 55. The trailing faceportion of the conventional gear tooth is shown and consists of thecombination 56 and 57; the latter being illustrated in broken line.

The driving pinion 15 includes a plurality of involute gear teeth 16which relative to the pitch circle 58 of the driven pinion, and like thesaw blade, display leading and trailing flanks 59, 60, respectively,leading and trailing faces 61, 62, respectively, and top lands 63.

Pitch circles 51 and 58 coincide or meet at 64 and are themselvesbisected by broken line 65 which is a line running through the centersof rotation (not shown) of pinion 15 and circular saw blade 13A allaccording to conventional gear layout.

As best illustrated with reference to the upper cutting tooth 50 seen inFIG. 11, a cut out 66 in the leading face portion extends from theproximate juncture of leading face 54 and flank 52 to cutting edge ortip 67 on the proximate top land 55. Compared to a profile of a standardgear tooth, the cutting edge 67 is set back a distance indicated byopposed arrows 68 which distance is sufficient to avoid contact of thecutting edge 67 with the trailing flank portion 60 of drive pinion 15.This is best seen with reference to cutting projection 50 located at thecommon point of pitch circles 51 and 58 and line 65.

As also seen in FIG. 11 and more particularly with reference to theupper cutting tooth 50, a clearance angle α is established between theactual top land 69 and the normal top land 55 of a conventional geartooth in order to facilitate entry into the work piece to be cut as iswell known in the art. Further, the cutting tip 67 can form part of areplaceable cutter 70 secured to projection 50 in a known manner such asattachment screws (not shown). Further, the cut out 66 and moreparticularly the replaceable cutter 70 can be so modified to give therake angles as the cutting dictates may require.

With reference to FIG. 12, the same reference numerals of FIG. 11 applyfor like parts. However, in this particular embodiment, a cutter 50Awhich forms the actual top land 69 carries with it at either of its endscutting tips 67A and 67B. As before, cutter 50A is attached to theprojections in a known manner (not shown) and are thus removable,replaceable or, as seen in FIG. 12, reversible. When leading edge 67A isdull, the cutter or insert 50A is rotated so that cutting edge 67B ispresented for service.

As previously mentioned the engagement of the pinion 15 and the saw 13is open and, therefore, subject to accelerated wear and shock loadsbecause of contaminants such as dirt and wood chips. These negativeeffects can be reduced by cleaning devices such as those illustrated inFIGS. 6 and 7. Experience has shown, however, that such devices may notbe required if the correct pinion material is chosen. Steel, cast iron,and bronze may be useful in some cases but non-metallic substances suchas rubber or nylon appear preferable. Pinions made from basic nylonresins give an acceptable economic life because they can be produced atlow cost. They offer the prospect of increased strength throughreinforcement with fibres such as fibre glass as well as reduced wearthrough additon of lubricants such as PTFE. They minimize the wear onthe expensive saw member, reduce noise, and in the case of excessiveloads act as a sacrifical member to provide smash-up protection for therest of the components. If desired, the teeth of the pinion only may beformed from such material and in some manner connected to, for example,a metal hub but such attachment and construction is difficult andexpensive. The purpose of utilizing a plastics material, plasticmaterial, rubber or something similar, is because of the resiliency ofthe material which allows for some deflection when grit, dirt, chips, orthe like, get between the driving faces of the gear teeth on the pinionand the saw blade. Also, it is preferable that the pinion teeth bedamaged or worn as opposed to the teeth on the saw blade since thepinion is more easily and cheaply replaced. The pinion, as a matter offact, could be made from rubber or various rubber or synthetic rubbercompounds suitably reinforced. Also, by utilizing a plastics material,plastic material and/or rubber, the pinion can be molded as opposed tobeing shaped in a gear cutting machine. The resiliency of a nylon pinionalso cuts down substantially the noise normally encountered from a loosemesh of the gear teeth, loose meshing being desirable as it allows formore readily clearing of saw dust, chips, and the like encountered fromthe cutting operation.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A rim driven saw forcutting trees comprising a planar circular saw blade having combinedgear and cutting teeth around the outer periphery thereof and a powerdriven pinion mounted on a supporting frame, said pinion having gearteeth meshing with said combined gear and cutting teeth of the saw, saidsaw and pinion being disposed in substantially the same plane, one faceof each of said combined gear and cutting teeth on the saw being anactive profile of a standard gear tooth mating with teeth on the drivepinion and in the other face having a cutting edge thereon each of saidcombined gear and cutting teeth having a profile of a conventional geartooth that includes, relative to the direction of saw rotation, a topland portion, a leading and trailing face portion and a leading andtrailing flank portion wherein the leading face portion is modified by acut out which extends from a proximate a juncture of the leading faceand flank portions to a leading edge of a cutter located at intersectionof the said cut out portion and said top land.
 2. The rim drivencircular saw as claimed in claim 1 wherein said cutter edge is set backfrom a point of normal intersection of said top land and said face of aconventional gear tooth.
 3. The rim driven circular saw as claimed inclaim 2 wherein said top land portion includes a clearance angle cut outwhich extends away from said cutting edge.
 4. The rim driven circularsaw as claimed in claim 1 wherein said conventional gear tooth is in theform of an involute gear tooth.
 5. The rim driven circular saw asclaimed in claim 1 wherein each said combined gear and cutting toothincludes a replaceable cutter.
 6. A rim driven circular saw as in claim5 wherein said replaceable cutter is reversible and includes at leasttwo cutting edges.
 7. The rim driven circular saw as claimed in claim 1wherein said circular saw is a disc.
 8. The rim driven saw as defined inclaim 1 wherein said circular saw in an annulus.
 9. The rim drivencircular saw blade as claimed in claim 1 wherein said drive pinion hasconventional gear teeth.
 10. The rim driven circular saw as claimed inclaim 1 wherein said cutting edge is set back from a normal intersectionof said leading face and said top land of a conventional gear tooth adistance sufficient to avoid contact of said cutting edge with saiddriving pinion teeth.
 11. The rim driven circular saw as claimed inclaim 1 wherein the modifications to the leading face and the top landare such that a tooth of the driving pinion is always in contact with atleast one of said trailing portions and said leading portions when thedirection of rotation is reversed.
 12. The rim driven circular saw asclaimed in claim 1 wherein said gear teeth of said driving pinion andsaid combined gear and cutting teeth on the saw prior to modification,have an involute gear form.
 13. A rim driven saw as defined in claim 1wherein at least the teeth of the drive pinion are made of a softermaterial than that of the gear tooth portions of the saw.
 14. A rimdriven saw as defined in claim 13 wherein said drive pinion is made ofnon-metallic material.
 15. A rim driven saw as claimed as defined inclaim 14 wherein said drive pinion is made from a plastics material. 16.A rim driven saw as defined in claim 15 wherein said plastics materialis nylon.
 17. A rim driven saw for cutting trees comprising a planarcircular saw blade having combined gear and cutting teeth around theouter periphery thereof and a power driven pinion mounted on asupporting frame, said pinion having gear teeth meshing with saidcombined gear and cutting teeth of the saw, said saw and pinion beingdisposed in substantially the same plane, one face of each of saidcombined gear and cutting teeth on the saw being an active profile of astandard gear tooth mating with teeth on the drive pinion and in theother face having a cutting edge thereon and means for clearing debrissuch as chips and the like from between the teeth on the saw, said meanscomprising an idler sprocket having formations projecting therefrom andmating with the teeth on the saw to extrude material caught therebetweenand propel the same through suitable openings in the supporting frame.18. A rim driven saw for cutting trees comprising a planar circular sawblade having combined gear and cutting teeth around the outer peripherythereof and a power driven pinion mounted on a supporting frame, saidpinion having gear teeth meshing with said combined gear and cuttingteeth of the saw, said saw and pinion being disposed in substantiallythe same plane, one face of each of said combined gear and cutting teethon the saw being an active profile of a standard gear tooth mating withteeth on the drive pinion and in the other face having a cutting edgethereon and means for clearing debris from between the cuttingformations on the saw comprising an air jet directed downwardly andoutwardly relative to the driven saw and including a suitable opening insaid supporting frame to allow the chips to escape therethrough.
 19. Arim driven saw as defined in claim 1 wherein said support frame includesan arm portion, from which the saw blade projects, and a plateunderlying the saw and including bearing means supporting the saw onsaid plate.
 20. A rim driven saw as defined in claim 19 wherein saidbearing means comprises at least two annular bearings interposed betweenthe saw and said plate.
 21. A rim driven saw for cutting treescomprising a planar circular saw blade having combined gear and cuttingteeth around the outer periphery thereof and a power driven pinionmounted on a supporting frame, said pinion having gear teeth meshingwith said combined gear and cutting teeth of the saw, said saw andpinion being disposed in substantially the same plane, one face of eachof said combined gear and cutting teeth on the saw being an activeprofile of a standard gear tooth mating with teeth on the drive pinionand in the other face having a cutting edge thereon wherein said supportframe includes an arm portion, from which the saw blade projects, and aplate underlying the saw and including bearing means supporting the sawon said plate and including fluid flow passage means in said plate foruse in lubricating said bearing means.
 22. A felling head comprising incombination:(a) a frame having a grapple mounted thereon and comprisinga pair of jaw members, at least one of which is pivotally mounted on theframe for movement toward and away from the other and together providinga grapple jaw which may be selectively opened and closed to respectivelyreceive and grasp a standing tree, power means connected to said movablegrapple jaw members selectively to open and close said grapple; and (b)a severing device mounted on said frame below said grapple for severinga standing tree, said severing device comprising an anvil mounted onsaid frame, an arm pivotally mounted on said frame and including bearingmeans for supporting a circular saw, a rim driven circular sawjournalled for rotation on said bearing means and having combined gearand cutting teeth around the outer periphery thereof; a motor unitmounted on said arm and having a pinion mounted directly thereon, theteeth of said pinion meshing with the teeth on the circular saw fordriving the same, both said pinion and saw rotating in a commcn plane.23. A felling head as defined in claim 22 wherein said anvil is arcuate.24. A felling head as defined in claim 22 wherein said frame has a platemounted thereon for supporting the butt end of a plurality of cut treesand wherein said grapple is an accumulator grapple of the type whichincludes an additional arm for holding and accumulating trees as theyare cut.
 25. A felling head as defined in claim 24 wherein an edge ofsaid plate comprises said anvil.
 26. Apparatus for transversely cuttingelongate articles such as trees or the like and particularly standingtrees comprising:(a) a frame having an anvil thereon; (b) an armpivotally mounted on said frame and having an arcuate portion facing theanvil and a plate projecting from said arcuate portion, said platehaving annular bearing means for supporting a circular saw; (c) a rimdriven circular saw supported on said annular bearing means, pivotalmovement of said arm moving said saw towards said anvil for cutting anarticle disposed between the saw and the anvil and and movable awaytherefrom to receive another article to be cut, said rim driven sawhaving combined gear and cutting teeth around the outer peripherythereof projecting in a direction outwardly from the axis of rotation ofthe saw; and (d) a motor unit mounted on said arm and having a pinionmounted directly thereon, the teeth of said pinion meshing with theteeth on the circular saw for driving the same, said pinion and said sawbeing disposed in a common plane.
 27. Apparatus as defined in claim 26wherein said anvil is concave, such concavity facing the arcuate portionof said arm.
 28. Apparatus as defined in claim 26 wherein said anvil hasa sharpened edge facing said circular saw.
 29. Apparatus as defined inclaim 26 wherein said anvil comprises a flat plate.
 30. A rim drivencutter comprising:a circular saw and a drive pinion rotatable aboutrespective ones of a pair of spaced apart parallel axes, each of saidsaw and pinion having projections of gear tooth form about the peripherythereof with the teeth of one meshing with those of the other, the teethon said saw each having a cutting edge set back from the normalintersection of the face and the top land of the teeth, a plate carriedby a rigid frame and bearing means mounting said saw on said plate, saidplate having a thickness at least no greater than the kerf generated bythe driven member and wherein said pinion is fabricated from anon-metallic substance.
 31. A saw as defined in claim 30 wherein saidplate underlies a major central portion of the saw.
 32. A saw as definedin claim 30 wherein said pinion is molded from a plastics material. 33.A rim driven saw as defined in claim 30 wherein at least the teeth ofthe drive pinion are made of a softer material than that of the geartooth portions of the saw.
 34. A rim driven saw as defined in claim 33wherein said drive pinion is made of non-metallic material.
 35. A rimdriven saw as defined in claim 34 wherein said drive pinion is made froma plastics material.
 36. A rim driven saw as defined in claim 35 whereinsaid plastics material is nylon.
 37. A felling head comprising incombination:(a) a frame having a grapple mounted thereon comprising apair of jaw members, at least one of which is selectively movable awayfrom and toward the other and together providing a grapple jaw whichthus may be selectively open and closed to respectively receive andgrasp a standing tree, power means connected to said movable grapple jawmembers selectively to open and close said grapple; and (b) a severingdevice carried by said frame and located at a position below saidgrapple for severing a standing tree grasped by the grapple, saidsevering device being a rim driven cutter comprising: a circular saw anda drive pinion rotatable about respective ones of a pair of spaced apartparallel axes, each of said saw and pinion having projections of geartooth form about the periphery thereof with the teeth of one meshingwith those of the other whereby the pinion and saw are in a drive drivenrelationship, the teeth on said saw each having a cutting edge set backfrom the normal intersection of the face and the top land of the tooth,a plate carried by a rigid frame and bearing means mounting saidcircular saw on said plate, said plate having a thickness at least nogreater than the kerf generated by the driven member and located withinthe boundaries of such kerf and wherein said pinion is fabricated from anon-metallic substance, and power means drivingly connected to saiddrive pinion.
 38. A felling head as defined in claim 37 wherein therigid frame of the severing device is pivotally mounted on the frame ofthe felling head.
 39. A felling head comprising in combination:(a) aframe having a grapple mounted thereon and comprising a pair of jawmembers, at least one of which is pivotally mounted on the frame formovement toward and away from the other and together providing a grapplejaw which may be selectively opened and closed to respectively receiveand grasp a standing tree, power means connected to said movable grapplejaw members selectively to open and close said grapple; and (b) asevering device mounted on said frame below said grapple for severing astanding tree, said severing device comprising an anvil mounted on saidframe, an arm pivotally mounted on said frame and including bearingmeans for supporting a circular saw, a rim driven circular sawjournalled for rotation on said bearing means and having combined gearand cutting teeth around the outer periphery thereof; a motor unitmounted on said arm and being drivingly connected to a pinion gearhaving the teeth thereof meshing with the teeth on the circular saw fordriving the same, both said pinion and saw rotating in a common plane.40. Apparatus for transversely cutting elongate articles such as treesor the like and particularly standing trees comprising:(a) a framehaving an anvil thereon; (b) an arm pivotally mounted on said frame andhaving an arcuate portion facing the anvil and a plate projecting fromsaid arcuate portion, said plate having annular bearing means forsupporting a circular saw; (c) a rim driven circular saw supported onsaid annular bearing means, pivotal movement of said arm moving said sawtowards said anvil for cutting an article disposed between the saw andthe anvil and movable away therefrom to receive another article to becut, said rim driven saw having combined gear and cutting teeth aroundthe outer periphery thereof projecting in a direction outwardly from theaxis of rotation of the saw; and (d) a motor unit mounted on said armand being drivingly connected to a pinion gear having the teeth thereofmeshing with the teeth on the circular saw for driving the same, saidpinion and said saw being disposed in a common plane.